Porphyria

Porphyrias: a group of photosensitivity disorders resulting from an inherited or acquired defect in the enzymes required to produce adequate amounts of haem, with the subsequent accumulation of porphyrins

Main groups

• Phototoxic skin porphyria (e.g. erythropoietic protoporphyria)

• Blistering and fragility skin porphyrias

• Acute attack porphyrias (some with no skin involvement, some also cause blistering and fragility)

• Severe congenetial porphyria (e.g. congenital erythropoietic porphyria)

Acute intermittent porphyria

• Most commonly presents in females around the age of 30

• Enzyme deficiency - porphobilinogen deaminase

• Porphyrin accumulated - porphobilinogen

Clinical presentation

• Acute abdomen

• Mood disturbance

• Neurological

• Seizures

• Unlikely to actually present with cutaneous symptoms

Porphyria cutanea tarda

• Most common type of porphyria

• Usually seen in middle aged men

• Commonly associated with liver disease, so often seen in those with haemochromatosis, hepatitis or alcohol misuse

• Enzyme deficiency - uroporphyrinogen decarboxylase

• Porphyrin accumulated - uroporphyrinogen

Clinical presentation

• Blistering lesions on sun exposed sites that heal with scarring and are associated with hyper pigmentation

• Also: hypertrichosis, solar urticaria, morphoea

Investigations

• Bloods - porphyrin studies

• Woods lamp - urine shines pink instead of blue

Management

• Establish and treat the underlying cause - alcohol, viral hepatitis, oestrogens, haemachromatosis

Erythropeotic protoprophyria

• Autosomal dominant

• Most commonly seen in children

• Enzyme deficiency - ferrochelatase

• Porphyrin accumulated - protoporphyrin IX

Clinical presentation

• There may be no evident rash but there will be burning and itching on the skin with sun exposure

• Typical presentation is child screaming when they are placed out in the sun

Investigations

• Quantitative RBC porphyrins

• Flurocytes (patient, relatives)

• Transaminases

• [Hb], red cell indices

• Biliary tract USS

• Phototesting

Management

• 6 monthy LFTs and RBC porphrins

• Visible light photoprotection measures

• Prophylactic TL-01 phototherapy

• Antioxidants

• Avoid iron

• Incipient liver failure - oral charcoal, cholestyramine, ASA synthase inhibition

• Liver failure - liver transplant

Summary